I create all my Killers (Assassins and Jigsaws) manually, and use SumoCue to validate and rate it. I keep rearranging the cages until the puzzle has the required difficulty, while it can still be solved by the program.

This puzzle was a lucky hit. The killer pairs just fell into place. I only needed to glue a few cages together to avoid an easy solution.

Ruud_________________If the human brain were so simple that we could understand it, we would be so simple that we couldn't. - Emerson M Pugh